The invention relates to a sheet feeding and separating device for use in an imaging transport apparatus, such as a document scanner, fax machine, or photocopier; more particularly to a sheet feeding and separating device with sensors for monitoring sheet feeding, and preventing sheet feeding and separating problems, such as multiple sheet feeding.
Most conventional sheet feeding devices used in imaging apparatus, such as document scanners, fax machines, and photocopiers, rely on friction to feed sheets into the imaging apparatus. These sheet feeding devices generally include a driven feed roller with a high friction surface, which is intended to feed a single sheet from a media stack, and a separation pad or roller, which is intended to prevent all of the other sheets in the stack from also feeding through. However, misfeeds and multiple feeds do occur, which slows up the imaging transport process and causes problems for the operator of the apparatus.
Most sheet feeding devices are built with a particular set of parameters that govern feeding and separating functions of the device. These parameters can be optimized for only a limited range of sheet characteristics, such as friction. Unfortunately, successfully feeding hundreds or thousands of sheets into an imaging apparatus over time is not achieved by controlling one or two variables. Many sheet characteristics must be monitored and controlled in order to come close to error-free operation of a well-used imaging apparatus. Among the most common errors are multiple feeds, which are due to a sheet separating error, and sheet misfeeds, which are due to a feeding error.
Another sheet feeding problem occurs when the feeding device attempts to feed sheets that have been glued or taped together into the imaging apparatus. These sheets will not separate when they are fed. However, if they can be returned to the input area, the operator will be provided with an opportunity to separate them by hand.
Although a document and image scanner or other imaging apparatus may contain a means for detecting multiple feeds, it cannot actively reverse the unwanted sheets or actively change operating parameters. Such apparatus are only capable of stopping the document transport and/or alerting the operator when a multiple feed occurs.
Scanners with mechanisms for detecting multiple feeds normally only have one such mechanism. Such mechanisms for detecting multiple feeds accommodate only a specific subset of the range of documents which should be scanned. They generally cannot be relied upon to detect and avoid all, or even most, of the sheet feeding problems that arise in the course of using imaging apparatus.
The present invention is an intelligent document feeding and separating device for imaging apparatus, including document and image scanners, photocopiers, and fax machines, that is capable of determining when multiple sheets are being fed and remedying the problem. When multiple documents are being fed, this feeding device can automatically assess the problem and vary one or more of the parameters that govern the sheet singulation process in attempts to remedy the problem. The present device can reverse the feeding of problematic sheets or, optionally, all of the sheets in the feeder device. The present device actively monitors and adjusts governing parameters for the particular characteristics of the sheet(s) being fed, which greatly expands operating range. Feeding and separating errors are reduced and overall performance of the imaging apparatus is improved. The present device has expanded sensing capabilities so that it can more easily and clearly define and remedy the various feeding/separating problems commonly encountered in imaging apparatus.
The present invention also includes an intelligent method for feeding and separating sheets of media for an imaging apparatus. The method includes assessing the type of problem present (multiple feeds, misfeeds), reversing the feed roller direction, varying governing parameters, and repeatedly attempting to remedy the problem.
The present invention is a sheet feeding and separating mechanism for consistently separating an outermost sheet of media from a stack and feeding it to an imaging rendering apparatus, the feeding and separating device comprising:
a) sheet transport mechanism;
b) a feed mechanism for feeding sheets to the sheet transport mechanism, the feed mechanism being positioned so as to frictionally engage the outermost sheet of the stack to advance the sheet toward the sheet transport mechanism;
c) a separation mechanism positioned adjacent to the feed mechanism;
d) at least one drive mechanism in operable association with the feed or separation mechanisms for transmitting an intermittent drive force to the feed or separation mechanisms; and
e) at least one sensor device for measuring the thickness or density of the sheet or sheets to be fed, the sensor device being positioned adjacent to the feed mechanism;
wherein at least one of the sensor devices inputs to the feeding and separating device, which is adjustable to address feed-related problems encountered during operation.